Japan is hoping to have the wrecked Fukushima nuclear plant safely shuttered by the end of the year, but a little radioactive wrench just got dropped: inspectors have discovered evidence of very recent fission. That's bad news.

Xenon-133 and 135 were found in gas samples, Japan Times reports, isotopes that are created during nuclear fission reactions. This means the plant's still burning, and officials suspect the action's located within melted fuel that seeped from the reactor earlier this year—remember, the thing did suffer a partial meltdown.

The reaction was likely very small, but also very recent—those particular isotopes have half-lives of only several days at most. Does this mean the plant is going to blow up? No. Does it mean Fukushima is still dangerous and unstable? Yes. Japan has its work cut out for it if they want to kill the site anytime soon. [Japan Times]